Method for forming semiconductor device using multi-functional sacrificial dielectric layer
A composite dielectric layer including a nitride layer over an oxide layer serves the dual function of acting as an SMT (stress memorization technique) film while an annealing operation is carried out and then remains partially intact as it is patterned to further serve as an RPO film during a subsequent silicidation process. The need to form and remove two separate dielectric material layers is obviated. The nitride layer protects the oxide layer to alleviate oxide damage during a pre-silicidation PAI (pre-amorphization implant) process thereby preventing oxide attack during a subsequent HF dip operation and preventing nickel silicide spiking through the attacked oxide layer during silicidation.
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The present invention relates, most generally, to semiconductor devices and methods for manufacturing the same. More particularly, the present invention relates to an efficient method for annealing a semiconductor structure using the same sacrificial dielectric layer that will be used as a resist protect dielectric for a subsequent silicidation process.
BACKGROUNDIn today's semiconductor manufacturing industry, it is critical to produce devices as rapidly as possible and as inexpensively as possible. A corollary to this is that it would be advantageous to produce any particular semiconductor device with a process fabrication sequence that involves the fewest number of processing operations and using the least amount of processing materials. It would clearly be advantageous to produce semiconductor devices with the same functionality, the same yield, and of the same quality, using a reduced number of processing operations and fewer processing materials.
According to conventional technology, when a semiconductor structure such as a transistor is annealed, a dielectric layer of one or more dielectric materials is maintained intact during the annealing process. The dielectric layer may serve as a stress memorization layer. This dielectric layer is then removed and a further dielectric is formed to use as a RPO (resist protect oxide) layer. The RPO is commonly formed over various structures and regions to protect the same during subsequent processing operations performed on the other structures and regions of the semiconductor substrate. The RPO may be patterned to expose portions of the underlying structures to be silicided, while protecting other portions from silicide formation during the subsequent silicidation process. This represents an area in which it would be beneficial to reduce the number of process operations and materials used. The present invention addresses this concern.
Another shortcoming associated with semiconductor manufacturing is related to the PIA (pre-amorphization implant)/silicidation process sequence. Conventionally, when an RPO oxide is formed and patterned prior to a silicidation process, the RPO oxide film becomes undesirably damaged during the pre-amorphization implant (PAI) advantageously used to amorphize exposed silicon surfaces prior to silicidation and while the RPO oxide is still in place. The RPO oxide damaged by the pre-silicidation PAI, is then undesirably attacked and removed by the conventionally-used pre-silicidation HF dip. This can cause silicide spikes in undesired areas especially when low activation energy metals such as nickel are used, and represents a further shortcoming in semiconductor manufacturing.
SUMMARY OF THE INVENTIONTo address these and other needs and in view of its purposes, the present invention provides a method for forming a semiconductor device. According to one aspect, the method includes forming a gate structure over a semiconductor substrate and forming a dielectric material over the semiconductor substrate including over the gate structure. The method provides for maintaining the dielectric material over the gate structure during a rapid thermal annealing operation and also maintaining the dielectric material over portions of the gate structure and the semiconductor substrate while siliciding other portions of at least one of the semiconductor substrate and the gate structure.
According to one aspect, the dielectric material may be a silicon nitride layer formed over an oxide layer. The silicon nitride layer may include a tensile stress according to one exemplary embodiment.
According to another aspect, the invention provides a method for forming a semiconductor device, the method including forming a gate structure over a semiconductor substrate and forming a dielectric composite over the semiconductor substrate including over the gate structure. The method also provides for maintaining the dielectric composite over the semiconductor substrate and gate structure during rapid thermal annealing and removing the dielectric composite from first areas to be silicided thereby forming a patterned dielectric composite over second areas not to be silicided. The method further provides for performing a pre-amorphization implant (PAI) process and forming silicides in the first areas during a silicidation process in which the dielectric composite prevents silicidation in the second areas.
The present invention is best understood from the following detailed description when read in conjunction with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not necessarily to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Like numerals denote like features throughout the specification and drawing.
Prior to an annealing operation that will be carried out to anneal source/drain regions 10, composite dielectric layer 18 is formed over substrate 2 and semiconductor device 4 as shown in
An annealing operation is carried out upon the structure shown in
A wet etching operation may be carried out upon the structure shown in
In the pre-silicidation HF dip illustrated in
After the “wet” HF dip shown in
The preceding merely illustrates the principles of the invention. If will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended expressly to be only for pedagogical purposes and to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure.
This description of the exemplary embodiments is intended to be read in connection with the figures of the accompanying drawing, which are to be considered part of the entire written description. In the description, relative terms such as “lower,” “upper,” “horizontal” “vertical,” “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the device is formed in a particular orientation.
Although the invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the invention, which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention.
Claims
1. A method for forming a semiconductor device, said method comprising:
- forming a gate structure over a semiconductor substrate; and
- forming a dielectric material comprising a composite layer of a silicon nitride layer over an oxide layer, over said semiconductor substrate including over said gate structure such that said silicon nitride layer is formed to include a tensile stress and impart said tensile stress upon a channel disposed beneath said gate structure;
- maintaining said dielectric material over said semiconductor substrate including over said gate structure during a rapid thermal annealing operation; and
- maintaining said dielectric material over portions of said semiconductor substrate and said gate structure during a silicidation operation, while siliciding other portions of at least one of said semiconductor substrate and said gate structure during said silicidation operation.
2. The method as in claim 1, further comprising maintaining said dielectric material over said portions of said gate structure and said semiconductor substrate during a pre-amorphization implant carried out before said silicidation and in which said pre-amorphization implant at least partially amorphizes exposed silicon surfaces in said other portions but does not damage said dielectric material.
3. The method as in claim 2, wherein said pre-amorphization implant includes an implant energy of at least 15 KeV, a dose of at least 2E13 atoms/cm2, and includes implanting at least one of argon, gallium, indium, germanium, and thallium.
4. The method as in claim 2, further comprising contacting said substrate with a wet HF solution while maintaining said dielectric material over portions of said gate structure and said semiconductor substrate and prior to said siliciding.
5. The method as in claim 1, wherein said dielectric material is maintained over said semiconductor substrate but not said gate structure during said silicidation operation and wherein said silicidation operation comprises forming a nickel silicide on exposed portions of said gate structure.
6. A method for forming a semiconductor device, said method comprising:
- forming a gate structure over a semiconductor substrate;
- forming a dielectric composite of a silicon nitride layer over an oxide layer, over said semiconductor substrate including over said gate structure such that said silicon nitride layer is formed to include a tensile stress and impart said tensile stress upon a channel disposed beneath said gate structure, and maintaining said dielectric composite thereover during rapid thermal annealing;
- removing said dielectric composite from first areas to be silicided thereby forming a patterned dielectric composite over second areas not to be silicided;
- performing a pre-amorphization implant process with said patterned dielectric composite in place; and
- forming silicides in said first areas during a silicidation process with said dielectric composite preventing silicidation in said second areas during said silicidation process.
7. The method as in claim 6, wherein said pre-amorphization implant includes implanting at least one of argon, gallium, indium, germanium, and thallium.
8. The method as in claim 6, wherein said pre-amorphization implant includes an implant energy of at least 15 KeV and an implant dose of at least 2E13 atoms/cm2 and at least partially amorphizes exposed silicon surfaces in said first areas.
9. The method as in claim 6, wherein said oxide layer is formed by chemical vapor deposit and includes a thickness of at least 50 angstroms and said silicon nitride includes a thickness of at least 300 angstroms.
10. The method as in claim 6, wherein said removing comprises plasma etching said silicon nitride layer and terminating said plasma etching using automatic endpointing techniques, and wet etching to remove said oxide layer.
11. The method as in claim 6, further comprising contacting said substrate with a wet HF solution after said pre-amorphization implant and prior to said forming a silicide and wherein said pre-amorphization implant and said exposing said substrate to said wet HF solution does not attack said oxide layer.
12. The method as in claim 6, wherein said silicides comprise nickel silicide.
13. The method as in claim 6, wherein said rapid thermal annealing includes a maximum temperature within the range of 1100-1200° C.
14. The method as in claim 6, wherein said forming silicides in said first areas with said dielectric composite preventing silicidation in said second areas, comprises forming a metal film over said patterned dielectric composite and said semiconductor substrate including said gate structure, then heating.
6040223 | March 21, 2000 | Liu et al. |
6187655 | February 13, 2001 | Wang et al. |
6326289 | December 4, 2001 | Rodder et al. |
6348389 | February 19, 2002 | Chou et al. |
6569784 | May 27, 2003 | Wang et al. |
6653191 | November 25, 2003 | Yang et al. |
6855592 | February 15, 2005 | Lee |
6989302 | January 24, 2006 | Makovicka et al. |
20040209432 | October 21, 2004 | Ku et al. |
20060228843 | October 12, 2006 | Liu et al. |
1423317 | June 2003 | CN |
Type: Grant
Filed: Jun 6, 2007
Date of Patent: Aug 31, 2010
Patent Publication Number: 20080305601
Assignee: Taiwan Semiconductor Manufacturing Co., Ltd. (Hsin-Chu)
Inventor: Jyh-Huei Chen (Hsinchu)
Primary Examiner: Michael Trinh
Attorney: Duane Morris LLP
Application Number: 11/758,897
International Classification: H01L 21/336 (20060101);